This grant concerns the characterization of the function of various cytomegalovirus proteins with potential or likely roles in DNA replication. Three functions, UL44, UL84 and UL112-113 will be the initial proteins to be studied. For each, null mutants and alleles carrying targeted mutations will be studied within the context of viral infection. UL44 is the polymerase processivity factor, and the goal is to dissect the functions of those portions of the protein required for processivity factor activity as well as those that are not. UL84 is an enigmatic activity that is unique to CMV. UL112-113 is a complex region that undergoes differential splicing.